Testing systlm



To all whom it may omwem I citizen of the United States of America, reduced by the contacts under test is standard,

the needle of the volmeter will remain prac-.

Patented M is, 1926. STATES own a. lumen, or .B'mooxnnr, n'nw- Yonx, assrexon ro wnsrnan' I COIPANY, ncoaronarnnor nnw Yonx; N. Ya: conrcBA'rIor or-nnw. You,

'rrsrme ers'rmr.

- Application filed larch aaim. lei-1a! at. 701,004.

Be it known that I, OHMEB R. Minna," a

siding at Brookl in the county of Kings, State ofNew ork, have invented certain new and useful Im rovements in Testin Systems, of which .t e following is a ful, clear, concise, and exact description."

This invention relates to a method and system for testing time intervals and partic'- ularly to the measuring of percentage of;

break to make of a circuit interrupting device such as the sending device. used in automatic telephone systems.

I An ob'ect of the invention is to provide a system t at produces a quick and accurate indication of this operating characteristic.

when short trainsof fast interruptions are 1 tested as well as when longer trains of comparatively slow interruptions are under test.

- Another object is to provide means ina systemof this'type for comparing a measured characteristic with any desired standard operating requlrement. I

This invention contemplates the use of acondenser and a volt-meter connected in para allel in a-circuit containing asource ofcurrent and the contacts of which the percentage of make to break-is to be -measured.-

The alternate closing and opening of these contacts will, in a circuit of this type, cause the condenser to accumulate a charge or discharge through' the voltmeter alternately and the voltmeter is so designed that theneedle thereof will indicate the average charge on. the, condenser. This indication thus represents the percentage of; make to breakof the contacts under test and may be so readon the dial of the voltmeter. It is,{ however, evident that when shorttrains of interruptions are under test, thevoltmeter' needle willh'ot respond'withsufiicient speed '5 permit the needle to quickly assume to secure an accurate reading before the-interruptionshave ceased. It is, therefore, a

feature of this invention to provide a relay arrangement to cause the needle to;assume a position before the test begins to represent a standardcondition or to assume a'position.

that is sufliciently close to the average charge to be produced by the contacts to be telsited to t 'e correct position when the test begins. To this end, a balanced circuit is provided which is connected to the condenser and the voltmeter before the test begins so as to estab- I ings of short trains lish this average charged condition. If,

new the percentage of make to break prostandard. In other words, with this arrangement the needle will occupy a position before the test begins which is in the vicinity of the position it will occupy when the test is made and thus comparatively quick readof impulses may be secured.- Another feature of the invention is th provision of adjusting means for the balanced circuit so arranged thatthegneedle may beset by repeated tests of theoperatmg charecterlstics of a particular pair of. in-

terrupting contacts at the exact position representing the ercentage of make to break of these contacts andthus an extremely accurate reading may be made of operating characteristics, regardless of the number of cycles of interruption.

Theinvention may be described in connection withjthe accompanying drawing in which Fig. 1 represents a circuit arran ement-b means of which the tests may e made; ig..2 represents a curve'of the process'involved, andFig. 3 shows a modified form Ofthecircuit for automatically setting the device for testing.

Referring" now toFig. 1,- the testing circuit proper comprises a condenser 10, a

voltmeter-11 in parallel therewith, a source of battery 12 and a dial 13 having interrupting contacts 14 in series therewith. A variable resistance 15 is also included in this circuitto regulate the time constant for charging the condenser, an expedient well known in the art. A key 16 is provided for connecting a source of battery and ground for the operation of the circuit shown, this key belng normally open so as to prevent current drains when the device is not in use. The balanced circuit normally connected to the condenser 10 consists of a variable resistance 17connected at one end-- to ground b the adjustable tag 18 and at the other en to the battery 19 t tacts. of key 16. A 'relay20 is provided to remove this balancing circuit from: the con-f circuit ing the test-ing operations as will be hereinafter described.

The operation of this device is as follows:

Key 16 is first permanently closed to ground and-battery followed by a momentary operation of start key tion of key 16 connects the battery to the balanced circuit softhat the condenser con-, nected through contacts of relay 20 to the midpoint 23 of this circuit will receive a charge corresponding to the potential at this point. "This charging circuitmay be traced from the midpoint "'23, right armature and back contact of relay 20, resistance 15, condenser 10, ground; at battery. 12. This char e on condenser 10 now represents the stand quired in senders such as 13. It should be observed that at the same time as ingprocess takes vplace, the operation 0- key 16 and the momentary operation of key.

22 has established a circuit for the energization of relay 21 as follows: grounded battery 12, interrupting contacts 14, .lefthand armature and back contact of relay 20, windin of'relay 21 therefore prevents, at its armature and back contact, the operation of relay 20 at this time. I

The circuit is now set for the testing of the interrupting contacts 14- to begin. If nowthe dial 13 is operated, the first break of contacts 14 releases relay 21 which in time causes relay 20 to operate from grounded battery12, winding of relay 20, armature and back contact of relay 21, contacts of start key .22, contacts of key 16 to ground. The operation of relay 20 now closes the testingcircuit at its left-hand armature and front contact and at its righthand armature and back'contact opens the circuit for condenser 10 to midpoint 23 of thebalanced circuit. Condenser 10 now begins to discharge through the voltmeter 11 which would ordinarily if continuedrcausc the needle. thereof to. swing towards its normal position. However, in the case where the percentage of break to make is standard no'defle'ction .of the needle will take place as thecontacts 14' will again close before any appreciable discharge is effected. In this case, therefore, the condenser will begin to receive a charge e ual to twice the amount of thedischarge an the needle will consequently remain stationary. .That is,

MZMQB if-the contacts-14 are p ratin 'ar d percentage of brea to ma rough con:

described. A

22. The operaard percentage of make to break rem this chargthe condenser would I to ground'atthe contacts o key.16. Relay 21 is operated and .That is,

at the stand-' e, the needle Wlll remain stationary partly due to itsf' inherent s'luggishness and part1 due to the 7 relative time and speed at whic the charging and discharginglmay take place. 'Thls. re ation is not on y de n'dent on the inherent characteristlcs o the apparatus employed but also on the adjustment of the. resistance 15 which may be set to accommodate series standard percentage relations.

On the other hand, in case the operating; characteristics of the-contacts 14 are not standard, theposition of the needle would}: be disturbed-and the accumulative effect of 80. I an unstandard condition wopld be indicated 3 by the needle. For example;-.if the percent-"T age of make is larger. than thd, standard, the condenser will have time toreceivea Pl'07 pcrtionally greater charge and a corres ondingly shorter tLme in which to disc arg'e and the needle of the .voltmeter will, there fore, show a gradually accumulating charge by a rising movement awayfrom its original position. Should tlie condition be the re: verse, that is, the closing time of the contacts 14 be less than the standard, the corf N respondingly gradual decreasing char e on i be afl'ected an the] needle swung; toward normal position showing thereby the accumulative effect of the I error in th1s direction. Thus, by setting the device in accordance with the above method,

the operatin characteristic an dthe percentage of error accurately meas-r ure It is evident that h means of this device the exact percentage of make to break of a particular sender may be quickl' ascertained 1 1 even though asingle break an make operation is tested. The manipulation of the device to perform this test will now be as scribed. The procedure is the same as in testing for a standard condition: 'with the 1 difference that several tests have to be made. v

at the first reading, the directionof error is noted on the volt-meter and then,

the device is adjusteduntil a test does not' affect the position of the needle. If now the direction of error has been noted and before a second testing operation is begun the-resistance 17, when the midp0int'23 of this balanced circuit is connected to the con--- denser 10, is adjusted to roduce an accumulated charge on the con enser 10 that will place the needle of the voltmeter as near as possible at the position it assumed durin f the first testing operation a repeated test wiil show how closelythe new position of the 1 finally no movement of the needle is noticed. 7

of any Sender ma be quic 1y compared with a standard iii of the contacts 14' when only a limited number of interruptions take place. In fact,

by these means an accurate reading may be secured from a single cycle of operation, that is, the operating characteristics of the dial may be tested with the same-accuracy when merely a single cycle of operations takes place as when anumber of interruptions occurs. This accuracy cannot be obtained with an ordinary voltmeter and a simple interrupting circuit without the balanced circuit, as the needle of the voltmeter wouldat the first closing of such a circuit swing to a position indicating a full charge of the condenser 10 and when the first interruption takes place, the-needle would not swing back to its proper position in time to indicate the true percentage of make to break before the completion of an operation of the dial, this beingparticularly true in case of a limited number of interruptions. A circuit arrangement, according to this invention, will, therefore, indicate with extreme accuracy the opcrating characteristics of a sender regardless of the number of cycles of interruptions tested. Y

' To more clearly illustrate what is actually taking place in this circuit when the operating characteristics of the sender are ascertained, Fig. 2 has been. prepared. Assuming then that point 29 represents the position at which the condenser 10 begins to receive a charge from the midpoint 23 of the balanced circuit and curve 30 when it has reached the level of line 31 represents the standard charge on the condenser from this circuit, the vertical line 32 may indicate the'moment when the first separation of contacts 14 occurs while line 33 indicates the moment when relay 21 has released and relay 20 operated. At this moment condenser 10 begins to discharge through the voltmeter and the amount of the dischargeis represented by the curve 34. When now the contacts 14 are closed,. the condenser again begins to receive a charge andthis moment of closure is indicated by line 35 and the charge received represented by the curve 36 which charge is twice the amount of the discharge lll'tlle case'assumed. This charging of the condenser continues until contacts 14 again separate and this moment is indicated by line 37. The condenser nowbegins to discharge a second time and this discharge is represented by the curve 38. The distance between the line 37 and the line 39 indicates the period of break, if line 39 indicates the moment at which the contact again closes."

These alternate discharges and charges are continuedin this manner until thelast interruption'ofthe contacts 14. If, now, the amount of discharge as represented by curve 34 is equal to half that of the amount of charge as represented by curve 36 and the subsequent discharges and charges are equal and the voltmeter needleis of. such nature as not to respond to charges of this amplitude one Way or the other, it will, by maintaining its original position, indicate the average charge or discharge of the condenser. If this position of the needle is marked on the voltmeter interms of perccntage of break to make, an immediate in- 'By a further study of these curves it is readily seen that in case the percentages of break to make are of different proportions, for example, the break period is longer than 60% of the total period, the needle will move toward zero position away from the original average position or, if the make period is longer than 40% of the total period the needle will gradually move up beyond the original average position. The needle will thus indicate in each instance not only the percentage of error or deflection from the standard but also give an indication of the new position to which the needle should be set to receive an immediate correct reading of the operating characteristics of any particular pulsing contacts under test.

Elg. 3 illustrates an automatic starting circuitthat may be substituted for-the'start key 22 and comprises relay 40 in the volt-. meter circuit that does not operate during the operations of the starting circuit due to. its inherent sluggishness in responding to short impulses of current but that operates before the interruptions begin or after they are completed to open the circuit for relay 21 at its. armature and back contact. T bus, in a circuit where this arrangement is employed all that is necessary to set the device in operative condition is tooperate key 16. Then, for example, if relay 40' operates before relay 20 has had time to become energized, it is evident that when the interruptions of contacts 14 begin, the circuit will function as in the case where the start key has been momentarily operated to cause this circuit will be closed at the left-hand armature and front cbntact thereof andconsev quently relay 40 will receive a, current sufiicient to causeits operation and thusv attract its armature and open the'circuit' for relay before. Alsojwhen the interruptions-have ceased, relayj40will-operate, causing. the

momentary release of relay and operation of relay 21 so that the test may proceed .as liereinbefore set fortlnx- It is evident from cuit of this sort no resetting of the circuit is required atthe .end of a testing period as is necessary-when the start key 21 only is employed.

The invention claimed is:

' "'1. The method-of measuring percentage of'break to make in a'circuit interrupting device consisting in establishingza certain potential in a. circuit, disconnecting the i'means for establishing said potential, setting the interrupting device in' operation, 'con- ,necting it to the circuit in which the potential is established, and observing'the change in said potential. 1 v

2. A method of measuring percentage of break to make in' a' circuit interrupting device consisting in establishing a standard potential in a circuit for comparison, simultaneously disconnecting the means for establishing said standard potential, sett ng the circuit interrupting. device in operation and connecting'the' interrupting device .in circuit with said standard established potential, and obslerving the change in said standard potentia i i 3. The method of measuring percentage of break to make in a circuit interrupting device which consists in charging a condenser to a certain standard," permitting a source of battery to influence said'condenser in ac present on the condenser.

cordance with the percentage of. break to inake'of the interrupting device and then observing the condition of the charge as compared with the standard. 7

- 4; AJntlIDtl of measurin percentage of break to make in a circuit interrupting device which consists in observingthe quantity of electrical energy present after the inter- 'rupting device is set' in operation. as compared with-a standard quantity of "electrical energy. v

5. A method of measuring percentage of break to make in a circuit interrupting device which consists inobserviiig the charge present-on a condenser after the interrupt ing device has been set in operation as com-v pared with a standard charge originally 6. The method of comparing the relation of the open and closed periods of a circuit, as determined b an interrupting device, with a relation t at is known consisting in senting the known relation, then subjecting the condenserto charges for discharges-in};

accordance with therelation determined by" the interrupting device, measuri'i'ig the: aver age charge maintained on 7.. The 'method of compari cuit interrupting device wit [a relation that v I r r certain quantity ofelectrical energy to rethis that by the use of relay 40111 a test ClI\ S8Ilt1Ilg said standard relation,

ing said quantity of electrical ener to drains or additions in-accordancewit the electrical energy accumulated. p

then sub ect 1'0 c ns x: 1-. comparing-it with the known. charge; 'I e r v "the relation g, a of the, open and the closed anode of a cir- 5. is standard-which consists of accumulating a,

1 8. In asystein for measuring the percent.- H

age of break to make in an interrupting de- 'viceincluding a condenser, .means for establishinga standard charge. on said 0011- denser, and means Y said condenser, the method of establishing the tan'dardchargedcondition of the condenser for measuring charges on consisting in connecting a circuit having a T known potential to the condenser and disconnecting said circuit from the condenser when it is charged to said standard condition, and

the method of observing changes in said charge caused by the operation of the inj terrupting device consisting in connecting a voltmeteraeross the terminals of'said con-' denser;

9. A system for measuring the percentage of break't o make in an interruptin device com rism a condenser, a circuit t erefor,

a ba ance circuit, means for connecting the 5 midpoint Ofsflld balanced circuit to the circuit forthe condensertoestablish a charge thereon coresponding to the potential at said midpoint a circuit including a source "of Q energy and said interrupting device, means for disconnecting the balanced circuit and connecting the circuit for the interrupting device to, the condenser, and means for ohserving the change in the potential on said I condenser during terrupting device. v

' 10. A system for measuring percentage of break to make in an denser, a balanced circuit including a source of energy and resistance, means for connect- 1 g .a point in said balanced'circuit representing a certain potential to the circuit for r the condenser to establish a potential condition on saidconde'nser corresponding to said' condensercircu t,-and means for observing the operation of said ininterrpting device comprising a condensena circuit therefor including a resistance in series with theconits or simultaneously disconnecting said lished potential and that established by the circuit including the interrupting device when said device is operating.

11". A system for measuring percentage of break to make in a circuit for an interrupting device comprising a condenser, means for establishing a certain charge on said condenser normally connected thereto, a relay, means for operating said relay to simultaneously disconnect the charging means from the condenserv and connecting the circuit for the interrupting device, and

means for observing the difi'erence between the original-charge on the condenser and that established during the operation of said device.

12. A system for measuring percentage of break to make in a circuit for an interrupting device comprising a circuit including a condenser normally charged at a certain potential, means for comparing said charge with the charges produced by the operation of said interrupting device when the circuit therefor is connected to the condenser.v

13. A system for measuring percentage of break to make in a circuit including an interrupting device comprising a condenser, means for establishing a certain charge on said condenser including a key for starting the establishing of a charge, means for transferring the charged condenser from said charging means to a circuit including the interrupti device comprising a bat-. tery,-a relay an a key for causing the energization of said relay from said battery to effect said transfer, and means for observing the original charge on the condenser with that obtained by the circuit including the interrupting device when said device is operated. a

14. A system for measuring percentage of break to make in a circuit caused by an inincluded therein comprismeans for establishing a means for terrupting device ing a condenser, certain charge on the condenser, transferring the condenser from rupting. device, means for effectin said transfer when the interrupting dev ce beginsto operate, and means or observing the charges on the condenser caused by the 'in-' charging means -j from the condenser and" connectm the circuit including the circuit interru tmg device thereto, means included in the urea; for themterrupting device for said charging means to the circuit including an mtercompared with the original controlling the operation of said relay to cause it to become energized when the interruptlng device is first operated, means operated' 'by said relay for removing said terrupting device thereto, means included in the circuit for the interrupting device for controlling the operation of said relay to cause it to become energized when the interrupting device is first operated, means operated by said relay for removing said last mentioned means from further control over said relay, means for observing the effect of the operation of said circuit lnterrupting device on the charged condition of said condenser, and means for releasing said relay to restore the controlling means there for into circuit with the interrupting device, effective after an operation of said device has ceased.

17 A system for measuring percentage of break to make in a circuit caused by an interrupting device comprising a condenser,

means for establishing a certain charge on the condenser, a relay for removing said charging means from the condenser and connecting the circuit including the circuit interrupting device there-to, means included in the circuit for the interrupting device for said rela means for releasing said relay to restore t e controlling means therefor into circuit with the interrupting device operated automatically after the interrupting device has come to rest.

18. A system for measuring the percentage of break to make in a circuit caused by an interrupting device comprisin a condenser normallycharged at a certain potential vand a voltmeter in parallel therewith for observing the charges present on the condenser after the interrupting device has begun to operate. I

n witness whereof, I hereunto subscribe 1113y2'4name this 19th day of March A. D.,

OHMEKB M tER. 

